Acrylic-halogenated polyolefin copolymer adhesion promoters

ABSTRACT

The present invention is directed to a method for producing a copolymer and a copolymer product of the method. The copolymer is prepared by a controlled radical polymerization process, typically an atom transfer radical polymerization process, in which polymerizable alkene monomers are polymerized in the presence of a halogenated polyolefin macroinitiator. The copolymer product of this process is useful in a film-forming composition that adheres strongly to polyolefinic substrates and to which non-polyolefinic film-forming compositions strongly adhere. The copolymer can be applied to a substrate in an adhesion-promoting layer or can be incorporated into a film-forming composition, such as a primer, that contains additional resinous compounds.

FIELD OF THE INVENTION

The present invention relates to adhesion promoters that improveadhesion between film-forming coatings and adhesives and polyolefinicsubstrates. The adhesion promoters are prepared by controlled radicalpolymerization using a halogenated polyolefin as a macroinitiator.

BACKGROUND OF THE INVENTION

Polyolefins, such as polypropylene and polyethylene are used in a widevariety of molding applications including, for example, in preparationof molded parts for use in the automotive, industrial and appliancemarkets. The preparation of such molded articles generally includes thesteps of molding an article from the polyolefin resin and applying tothe molded article one or more film-forming coating layers to protectand/or color the article and/or an adhesive to attach the molded articleto another article.

One difficulty with use of poyolefinic substrates is that typicalfilm-forming coatings and adhesives do not adhere well to the substrate.In the case of a film-forming coating applied to the substrate, thelayer delaminates. In the case of adhesives, adhesive failure iscommonplace.

A solution to the failure of coatings and adhesives to adhere to thepolyolefinic substrate is to include a layer of a film-formingcomposition including a chlorinated polyolefin (CPO) between thesubstrate and the film-forming coating or adhesive. This adds aprocessing step and, since chlorinated polyolefins are relativelyexpensive, adding to the cost of using polyolefins to produce moldedparts.

U.S. Pat. No. 5,955,545 discloses use of CPO-acrylic graft copolymers asadhesion promoters that assertedly improve adhesion of subsequentcoating layers and/or adhesives to polyolefins. However, these graftcopolymer adhesion promoters are prepared by standard free radicalpolymerization methods and suffer from high polydispersity and thepresence of non-graft polymer chains and acrylic copolymers andhomopolymers in the resin composition as a result of the random natureof standard radical polymerization processes. The high polydispersityand additional non-graft chains present in the same mixture as the graftpolymer results in incomplete or inefficient adhesion promotion andinterference with the curing dynamics of the resin. Further, thesecompositions are unstable, readily falling out of solution, especiallywhen incorporated in a film-forming composition, and they absorb andscatter light, giving a hazy appearance. Thus, they are unsuitable formany coating applications.

It is, therefore, desirable to have well defined adhesion promotingmaterial that includes polyolefinic segments or portions that interactstrongly with polyolefinic substrates as well as portions ornon-polyolefinic segments that interact well with film-forming resins,crosslinkers and/or curing agents and solvents that are present in atypical coating composition. It is also desirable that the adhesionpromoter be of a more defined architecture than is typically found ingraft copolymers formed by a free radical process. The definedarchitecture will allow for design of copolymers that interact withother components of the coating composition in a consistent manner withless contamination with undesirable polymer species that typicallyresult from free radical grafting to CPOs. The low polydispersity of thematerial, combined with the substantial absence of undesirable polymerspecies would yield a clear, stable coating additive or coatingcomposition that would adhere well to polyolefinic substrates.

A wide variety of radically polymerizable monomers, such as methacrylateand acrylate monomers, are commercially available and can provide a widerange of properties including, for example, hydrophilic and hydrophobicproperties, the ability to interact with crosslinkers, or to selfcrosslink.

U.S. Pat. Nos. 5,807,937; 5,789,487; and 5,763,548 and InternationalPatent Publication Nos. WO 98/40415; WO 98/01480; WO 97/18247; and WO96/30421 describe a radical polymerization process referred to as atomtransfer radical polymerization (ATRP). The ATRP process is described asbeing a living radical polymerization that results in the formation of(co)polymers having predictable molecular weight and molecular weightdistribution. The ATRP process is also described as providing highlyuniform products having controlled structure (i.e., controllabletopology, composition, etc.). The '937 and '548 patents also describe(co)polymers prepared by ATRP, which are useful in a wide variety ofapplications including, for example, dispersants and surfactants.

U.S. Pat. Nos. 5,478,886; 5,272,201; 5,221,334; 5,219,945; 5,085,698;4,812,517; and 4,755,563 describe ABC, AB and BAB block copolymers andpigmented ink compositions containing such block copolymers. The blockcopolymers of the '886, '201, '334, '945, '698, '517 and '563 patentsare described as being prepared by living or stepwise polymerizationprocesses, such as anionic or group transfer polymerization.

A number of initiators and macroinitiators are known to support ATRPpolymerization. These initiators are described, for example, in U.S.Pat. Nos. 5,807,937 and 5,986,015. U.S. Pat. No. 5,807,937 discloses anumber of initiators, including a macroinitiator, where halide groupsattached to an activated benzylic carbon serve as the initiating site.The '937 patent discloses that benzyl halides can be efficientinitiators for ATRP in monomeric form as well as in a polymer.

WO 9840415 Al discloses ATRP macroinitiators having an activatedhalogen, which have been prepared by chlorosulfonation of polyethylene.The chlorosulfonyl group is known to be a good ATRP initiator inmonomeric form.

Paik et al. (“Synthesis and Characterization of Graft Copolymers of Poly(vinyl chloride) with Styrene and (Meth) acrylates by Atom TransferPolymerization”, Macromol. Rapid Commun., 19, 47-52(1998)) disclose thatpolyvinyl chloride is incapable of serving as an initiator in an ATRPprocess. Paik further discloses that ATRP can be initiated by theactivated chlorine in a chloroacetate group attached to a PVC backbone.Paik also discloses that the secondary chlorines on the PVC backbone donot initiate ATRP. Collectively, the prior art indicates that effectiveATRP macroinitiators should contain activated halogens.

SUMMARY OF THE INVENTION

In accordance with the present invention, an alkenyl (co)polymer isprovided that is prepared by polymerizing alkenyl monomers in thepresence of an initiator or macroinitiator (collectively “an initiator”)having halide groups attached to tertiary carbons under atom transferradical polymerization conditions. An example of such an initiator is,without limitation, a halogenated polyolefin such as a chlorinated orbrominated polypropylene, polybutylene or branched polyethylene. Thispolymer finds use in a variety of applications, such as, withoutlimitation, in compositions for coating, molding and extruding. Atypical use for the copolymer is as an additive to a film-forming resincomposition for coating a polyolefinic substrate. The additive bothpromotes interlayer adhesion between the coating composition layer andthe polyolefinic substrate and can be crosslinked into the film-formingresin.

A curable film-forming composition including the alkenyl-halogenatedpolyolefin copolymer is also provided. The halogen content of thehalogenated polyolefin embodiment is typically either chlorine orbromine. The number of halide groups in the initiator can vary, buttypically falls between about 15% to 45% by weight of the initiator, asis commonly found in commercially available halogenated polyolefins.

A method of coating a polyolefinic substrate also is provided thatincludes applying to the polyolefinic substrate a film-formingcomposition comprising the above-described vinyl-halogenated polyolefincopolymer. A coated article prepared according to the method is alsodescribed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Other than in the operating examples, or where otherwise indicated, allnumbers or expressions referring to quantities of ingredients, reactionconditions, etc, used in the specification and claims are to beunderstood as modified in all instances by the term “about”. As usedherein, the term “polymer”, and the like, is intended to include bothpolymers and oligomers unless stated otherwise. The term “copolymer” isintended to include both random or block copolymers unless specifiedotherwise.

As described above, the present invention is a polymeric compositionprepared by an ATRP process. The process utilizes a novel ATRP initiatorthat expands the type of copolymers that can be prepared by the ATRPprocess and the uses therefor. The initiator is a halogenatedpolyolefin, resulting in the production of a graft copolymer useful asan additive in a coating composition for polyolefinic substrates, amongother uses. By the term “polyolefinic substrate” it is meant as asubstrate having, on at least a portion of its surface, a polyolefiniccomposition.

The copolymer of the present invention is prepared by controlled radicalpolymerization. As used herein and in the claims, the term “controlledradical polymerization”, and related terms, e.g., “living radicalpolymerization”, refer to those methods of radical polymerization thatprovide control over the molecular weight, polymer chain architectureand polydispersity of the resulting polymer. A controlled or livingradical polymerization is also described as a chain-growthpolymerization that propagates with essentially no chain transfer andessentially no chain termination. The number of living polymer chainsformed during a controlled radical polymerization is often nearly equalto the number of initiators present at the beginning of the reaction.Each living polymer chain typically contains a residue of the initiatorat what is commonly referred to as its tail and a residue of theradically transferable group at what is commonly referred to as itshead.

In an embodiment of the present invention, the copolymer is prepared byatom transfer radical polymerization (ATRP). The typical ATRP processcan be described generally as including the steps of polymerizing one ormore radically polymerizable monomers in the presence of an initiationsystem; forming a polymer; and isolating the formed polymer. In thepresent invention, the initiation system comprises a halogenatedpolyolefinic initiator; a transition metal compound, i.e., a catalyst,which participates in a reversible redox cycle with the initiator; and aligand, which coordinates with the transition metal compound. The ATRPprocess is described in further detail in International PatentPublication WO 98/40415 and U.S. Pat. Nos. 5,807,937; 5,763,548 and5,789,487.

In the present invention, ATRP is performed using a polymer which hasnot been modified to introduce a known activated halogen group or has itbeen modified as the result of copolymerization of a monomer containinga known activated halogen group. Thus, in the present invention, anunmodified halogen containing polymer is the site for ATRP initiation.Post polymerization modification or inclusion of a special ATRPinitiating monomer are not required. This avoids additional processsteps in the first case and avoids making a special copolymer in thesecond.

There are a number of potential explanations as to the exact chemicalreason for ATRP functioning well in an unmodified halogen containingpolymer, without the presence of the prior art activated halogens.Without wishing to be bound to any single theory, it is believed thatthe inductive effect of other halogens on the main polymer chain inproximity to the initiating halogen is responsible for its ability toinitiate ATRP. Given the free radical nature of ATRP, it is believedthat the tertiary halogens on the polymer are the most prone to act asATRP initiation sites.

Catalysts that may be used in the ATRP preparation of the copolymer ofthe present invention include any transition metal compound that canparticipate in a redox cycle with the initiator and the growing polymerchain. It is preferred that the transition metal compound not formdirect carbon-metal bonds with the polymer chain. Transition metalcatalysts useful in the present invention may be represented by thefollowing general formula (I),

TM^(n+)X_(n)  (I)

wherein TM is the transition metal, n is the formal charge on thetransition metal having a value of from 0 to 7, and X is a counterion ora covalently bonded component. Examples of the transition metal (TM)include, but are not limited to, copper, iron, gold, silver, mercury,palladium, platinum, cobalt, manganese, ruthenium, molybdenum, niobiumand zinc. Examples of X include, but are not limited to, halide,hydroxy, oxygen, C₁-C₆-alkoxy, cyano, cyanato, thiocyanato and azido. Apreferred transition metal is Cu(I) and X is preferably halide, e.g.,chloride. Accordingly, a preferred class of transition metal catalystsare the copper halides, e.g., Cu(I)Cl. It is also preferred that thetransition metal catalyst contain a small amount, e.g., one molepercent, of a redox conjugate, for example, Cu(II)Cl₂ when Cu(I)Cl isused. Additional catalysts useful in preparing the polymer are describedin U.S. Pat. No. 5,807,937 at column 18, lines 29 through 56. Redoxconjugates are described in further detail in U.S. Pat. No. 5,807,937 atcolumn 11, line 1 through column 13, line 38.

Ligands that may be used in the ATRP preparation of the copolymerinclude, but are not limited to, compounds having one or more carbon,nitrogen, oxygen, phosphorus and/or sulfur atoms, which can coordinateto the transition metal catalyst compound, e.g., through sigma and/or pibonds. Classes of useful ligands include, but are not limited to,unsubstituted and substituted pyridines and bipyridines; porphyrins;cryptands; crown ethers, e.g., 18-crown-6; polyamines, e.g.,ethylenediamine; glycols, e.g., alkylene glycols, such as ethyleneglycol and carbon monoxide. As used herein and in the claims, the term“(meth)acrylate”and similar terms refer to acrylates, methacrylates, andmixtures of acrylates and methacrylates. A preferred class of ligandsare the substituted bipyridines, e.g., 4,4′-dialkyl-bipyridyls.Additional ligands that may be used in preparing the polymer aredescribed in U.S. Pat. No. 5,807,937 at column 18, line 57 throughcolumn 21, line 43.

The present invention utilizes novel macroinitiators that are typicallyhalogenated polyolefins. The initiator includes one or more ATRPinitiation sites that is a halide group attached to a tertiary carbon(hereinafter “tertiary halide”). A halide group that is capable ofserving as an ATRP initiation site, whether or not a tertiary, secondaryor primary halide, or otherwise, is hereinafter referred to as a“dormant halide”, as opposed to a halide that is not capable of servingefficiently as a site of ATRP initiation.

Suitable macroinitiators include, without limitation, halogenatedpolyolefins such as polypropylene and polybutylene. The halide group istypically chlorine and/or bromine. The macroinitiator also can be abranched polyethylene containing a suitable number of tertiary halides.

As used herein and in the claims, by “olefin” and like terms it is meantunsaturated aliphatic hydrocarbons having one or more double bonds, suchas obtained by cracking petroleum fractions. Specific examples ofolefins include, but are not limited to, propylene, 1-butene,1,3-butadiene, isobutylene and diisobutylene. A “polyolefin” is apolymer formed from olefins. Common examples are polypropylene andpolybutylene and include the class of thermoplastic polyolefins (TPOs).The polyolefin may be homopolymeric or copolymeric. A variety ofhomopolymeric halogenated polyolefins are available from EastmanChemical Company, among others. A halogenated polyolefin is ahalogen-substituted polyolefin, and is typically chlorinated orbrominated.

There is no literal limit as to the density of halides on the polyolefinbackbone of the initiator. However, the halogenated polyolefin typicallyis a chlorinated or brominated polyolefin having 15% to 45% by weighthalide groups, with at least about 80% of the halides being attached totertiary carbons and, therefore, being dormant halides. Halogenatedpolyolefins having 15% to 45% by weight halide groups represent mostcommercially available halogenated polyolefins. However, whenhalogenated polyolefins having 15% to 45% by weight, halide groups areused as ATRP initiators, the resultant ATRP-produced copolymers arepreferred as adhesion promoters for coating compositions used to coatpolyolefinic substrates. Having a higher density of halide groups on thepolyolefinic backbone of the initiator typically results in insufficientadhesion of copolymer-containing coating to the polyolefinic substrate.Too little halogenation of the polyolefinic backbone of themacroinitiator may result in poor compatibility of the copolymer withthe coating composition in which it is dispersed and lack of otherdesirable functionality in the copolymer, such as sufficientcrosslinking density. The most preferred halide group density on thepolyolefin initiator will depend upon the ultimate end use for theATRP-produced copolymer and, therefore, will vary from use-to-use.

Monomers that may be polymerized by the ATRP process of the presentinvention include all alpha, beta ethylenically unsaturated monomersthat are known to be capable of polymerization by the ATRP process. Anyradically polymerizable alkene containing a polar group can serve as amonomer for polymerization. The preferred monomers include those of theformula (II):

wherein R₄ and R₅ are independently selected from the group consistingof H, halogen, CN, CF₃, straight or branched alkyl of 1 to 20 carbonatoms (preferably from 1 to 6 carbon atoms, more preferably from 1 to 4carbon atoms), aryl, α,β-unsaturated straight or branched alkenyl oralkynyl of 2 to 10 carbon atoms (preferably from 2 to 6 carbon atoms,more preferably from 2 to 4 carbon atoms), α,β-unsaturated straight orbranched alkenyl of 2 to 6 carbon atoms (preferably vinyl) substituted(preferably at the α-position) with a halogen (preferably chlorine),C₃-C₈ cycloalkyl, heterocyclyl, phenyl which may optionally have from1-5 substituents on the phenyl ring, C(═Y)R₈, C(═Y)NR₉ R₁₀, YCR₉ R₁₀ R₁₁and YC(═Y)R₁₁, where Y may be NR₁₁ or O (preferably O), R₈ is alkyl offrom 1 to 20 carbon atoms, alkoxy of from 1 to 20 carbon atoms, aryloxyor heterocyclyloxy, R₉ and R₁₀ are independently H or alkyl of from 1 to20 carbon atoms, or R₉ and R₁₀ may be joined together to form analkylene group of from 2 to 5 carbon atoms, thus forming a 3- to6-membered ring, and R₁₁ is H, straight or branched C₁-C₂₀, alkyl andaryl; and

R₆ is selected from the group consisting of H, halogen (preferablyfluorine or chlorine), C₁-C₆ (preferably C₁) alkyl, CN, COOR₁₂ (whereR₁₂ is H, an alkali metal, or a C₁-C₆ alkyl group) or aryl; or

R₄ and R₆ may be joined to form a group of the formula (CH₂)_(n), (whichmay be substituted with from 1 to 2n′ halogen atoms or C₁-C₄ alkylgroups) or C(═O)—Y—C(═O), where n′ is from 2 to 6 (preferably 3 or 4)and Y is as defined above; or

R₇ is the same as R₄ or R₅ or optionally R₇ is a CN group; at least twoof R₄, R₅, and R₆ are H or halogen.

In the context of the present application, the terms “alkyl”, “alkenyl”and “alkynyl” refer to straight-chain or branched groups.

Furthermore, in the present application, “aryl” refers to phenyl,naphthyl, phenanthryl, phenalenyl, anthracenyl, triphenylenyl,fluoranthenyl, pyrenyl, pentacenyl, chrysenyl, naphthacenyl, hexaphenyl,picenyl and perylenyl (preferably phenyl and naphthyl), in which eachhydrogen atom may be replaced with alkyl of from 1 to 20 carbon atoms(preferably from 1 to 6 carbon atoms and, more preferably, methyl),alkyl of from 1 to 20 carbon atoms (preferably from 1 to 6 carbon atomsand, more preferably, methyl) in which each of the hydrogen atoms isindependently replaced by a halide (preferably a fluoride or achloride), alkenyl of from 2 to 20 carbon atoms, alkynyl of from 1 to 20carbon atoms, alkoxy of from 1 to 6 carbon atoms, alkylthio of from 1 to6 carbon atoms, C₃-C₈ cycloalkyl, phenyl, halogen, NH₂,C₁-C₆-alkylamino, C₁-C₆-dialkylamino, and phenyl which may besubstituted with from 1 to 5 halogen atoms and/or C₁-C₄ alkyl groups.(This definition of “aryl” also applies to the aryl groups in “aryloxy”and “aralkyl”.) Thus, phenyl may be substituted from 1 to 5 times andnaphthyl may be substituted from 1 to 7 times (preferably, any arylgroup, if substituted, is substituted from 1 to 3 times) with one of theabove substituents. More preferably, “aryl” refers to phenyl, naphthyl,phenyl substituted from 1 to 5 times with fluorine or chlorine, andphenyl substituted from 1 to 3 times with a substituent selected fromthe group consisting of alkyl of from 1 to 6 carbon atoms, alkoxy offrom 1 to 4 carbon atoms and phenyl. Most preferably, “aryl” refers tophenyl and tolyl.

In the context of the present invention, “heterocyclyl” refers topyridyl, furyl, pyrrolyl, thienyl, imidazolyl, pyrazolyl, pyrazinyl,pyrimidinyl, pyridazinyl, pyranyl, indolyl, isoindolyl, indazolyl,benzofuryl, isobenzofuryl, benzothienyl, isobenzothienyl, chromenyl,xanthenyl, purinyl, pteridinyl, quinolyl, isoquinolyl, phthalazinyl,quinazolinyl, quinoxalinyl, naphthyridinyl, phenoxathiinyl, carbazolyl,cinnolinyl, phenanthridinyl, acridinyl, 1,10-phenanthrolinyl,phenazinyl, phenoxazinyl, phenothiazinyl, oxazolyl, thiazolyl,isoxazolyl, isothiazolyl, and hydrogenated forms thereof known to thosein the art. Preferred heterocyclyl groups include pyridyl, furyl,pyrrolyl, thienyl, imidazolyl, pyrazolyl, pyrazinyl, pyrimidinyl,pyridazinyl, pyranyl and indolyl, the most preferred heterocyclyl groupbeing pyridyl. Accordingly, suitable vinyl heterocyclyls to be used as amonomer in the present invention include 2-vinyl pyridine, 4-vinylpyridine, 2-vinyl pyrrole, 3-vinyl pyrrole, 2-vinyl oxazole, 4-vinyloxazole, 5-vinyl oxazole, 2-vinyl thiazole, 4-vinyl thiazole, 5-vinylthiazole, 2-vinyl imidazole, 4-vinyl imidazole, 3-vinyl pyrazole,4-vinyl pyrazole, 3-vinyl pyridazine, 4-vinyl pyridazine, 3-vinylisoxazole, 3-vinyl isothiazoles, 2-vinyl pyrimidine, 4-vinyl pyrimidine,5-vinyl pyrimidine, and any vinyl pyrazine, the most preferred being2-vinyl pyridine. The vinyl heterocyclyls mentioned above may bear oneor more (preferably 1 or 2) C₁-C₆ alkyl or alkoxy groups, cyano groups,ester groups or halogen atoms, either on the vinyl group or theheterocyclyl group, but preferably on the heterocyclyl group. Further,those vinyl heterocyclyls which, when unsubstituted, contain an N—Hgroup may be protected at that position with a conventional blocking orprotecting group, such as a C₁-C₆ alkyl group, a tris-C₁-C₆ alkylsilylgroup, an acyl group of the formula R₁₃ CO (where R₁₃ is alkyl of from 1to 20 carbon atoms, in which each of the hydrogen atoms may beindependently replaced by halide, preferably fluoride or chloride),alkenyl of from 2 to 20 carbon atoms (preferably vinyl), alkynyl of from2 to 10 carbon atoms (preferably acetylenyl), phenyl which may besubstituted with from 1 to 5 halogen atoms or alkyl groups of from 1 to4 carbon atoms, or aralkyl (aryl-substituted alkyl, in which the arylgroup is phenyl or substituted phenyl and the alkyl group is from 1 to 6carbon atoms), etc. (This definition of “heterocyclyl” also applies tothe heterocyclyl groups in “heterocyclyloxy” and “heterocyclic ring”.)

More specifically, preferred monomers include (but are not limited to)styrene, p-chloromethylstyrene, vinyl chloroacetate, acrylate andmethacrylate esters of C₁-C₂₀ alcohols, isobutene, 2-(2-bromopropionoxy)ethyl acrylate, acrylonitrile, and methacrylonitrile.

The monomer containing at least one polar group may be present in anamount of 5 to 100 wt % by weight based on the total amount of monomers.A preferred amount of the monomer containing at least one polar group is10 to 100 wt %; the most preferred amount is 20 to 100 wt % based on thetotal amount of monomers. This is particularly important in the case ofacrylonitrile because an amount of at least 20 wt % assures solventresistance properties of the resulting polymer A.

Examples of suitable monomers may each be independently selected fromvinyl monomers, allylic monomers, olefins, (meth)acrylic acid,(meth)acrylates, (meth)acrylamide, N- and N,N-disubstituted(meth)acrylamides, vinyl aromatic monomers, vinyl halides, vinyl estersof carboxylic acids and mixtures thereof. More specific examples ofsuitable monomers include, without limitation, C₁-C₂₀ alkyl(meth)acrylates (including linear or branched alkyls and cycloalkyls)which include, but are not limited to, methyl (meth)acrylate, ethyl(meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl(meth)acrylate, iso-butyl (meth)acrylate, tert-butyl (meth)acrylate,2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, isobornyl(meth)acrylate, cyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl(meth)acrylate and isocane (meth)acrylate; (meth)acrylate esters ofC₁-C₂₀ alcohols; oxirane functional (meth)acrylates which include, butare not limited to, glycidyl (meth)acrylate,3,4-epoxycyclohexylmethyl(meth)acrylate, and 2-(3,4-epoxycyclohexyl)ethyl(meth)acrylate; hydroxy alkyl (meth)acrylates having from 2 to 4carbon atoms in the alkyl group which include, but are not limited to,hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate andhydroxybutyl (meth)acrylate. The residues may each independently beresidues of monomers having more than one (meth)acryloyl group, such as(meth)acrylic anhydride, diethyleneglycol bis(meth)acrylate,4,4′-isopropylidenediphenol bis(meth)acrylate (Bisphenol Adi(meth)acrylate), alkoxylated 4,4′-isopropylidenediphenolbis(meth)acrylate, trimethylolpropane tris(meth)acrylate and alkoxylatedtrimethylolpropane tris(meth)acrylate.

Specific examples of vinyl aromatic monomers that may be used to preparethe polymer include, but are not limited to, styrene, p-chloromethylstyrene, divinyl benzene, vinyl naphthalene and divinyl naphthalene.Vinyl halides that may be used to prepare the graft copolymer include,but are not limited to, vinyl chloride and vinylidene fluoride. Vinylesters of carboxylic acids that may be used to prepare the graftcopolymer include, but are not limited to, vinyl acetate, vinylbutyrate, vinyl 3,4-dimethoxybenzoate and vinyl benzoate.

As used herein and in the claims, by the term “allylic monomer(s)” it ismeant monomers containing substituted and/or unsubstituted allylicfunctionality, i.e., one or more radicals represented by the followinggeneral formula III,

H₂C═C(R₁)—CH₂—  (III)

wherein R₁ is hydrogen, halogen or a C₁ to C₄ alkyl group. Mostcommonly, R₁ is hydrogen or methyl and consequently general formula IIIrepresents the unsubstituted (meth)allyl radical. Examples of allylicmonomers may each independently be residues that include, but are notlimited to, (meth)allyl ethers, such as methyl (meth)allyl ether and(meth)allyl glycidyl ether; allyl esters of carboxylic acids, such as(meth)allyl acetate, (meth)allyl butyrate, (meth)allyl3,4-dimethoxybenzoate and (meth)allyl benzoate.

Other ethylenically unsaturated radically polymerizable monomers thatmay be used to prepare the copolymer include, but are not limited to,cyclic anhydrides, e.g., maleic anhydride,1-cyclopentene-1,2-dicarboxylic anhydride and itaconic anhydride; estersof acids that are unsaturated but do not have α,β-ethylenicunsaturation, e.g., methyl ester of undecylenic acid; diesters ofethylenically unsaturated dibasic acids, e.g., di(C₁-C₄ alkyl)ethylmaleates; maleimide and N-substituted maleimides.

In an embodiment of the present invention, the monomer includes ahydrophobic residue of a monomer selected from oxirane functionalmonomer reacted with a carboxylic acid selected from the groupconsisting of aromatic carboxylic acids, polycyclic aromatic carboxylicacids, aliphatic carboxylic acids having from 6 to 20 carbon atoms andmixtures thereof; C₆-C₂₀ alkyl (meth)acrylates, e.g., including those aspreviously recited herein; aromatic (meth)acrylates, e.g., phenyl(meth)acrylate, p-nitrophenyl (meth)acrylate and benzyl (meth)acrylate;polycyclicaromatic (meth)acrylates, e.g., 2-naphthyl (meth)acrylate;vinyl esters of carboxylic acids, e.g., hexanoic acid vinyl ester anddecanoic acid vinyl ester; N,N-di(C₁-C₈ alkyl) (meth)acrylamides;maleimide; N-(C₁-C₂₀ alkyl) maleimides; N-(C₃-C₈ cycloalkyl) maleimides;N-(aryl) maleimides; and mixtures thereof. Examples of N-substitutedmaleimides include, but are not limited to, N-(C₁-C₂₀ linear or branchedalkyl) maleimides, e.g., N-methyl maleimide, N-tertiary-butyl maleimide,N-octyl maleimide and N-icosane maleimide; N-(C₃-C₈ cycloalkyl)maleimides, e.g., N-cyclohexyl maleimide; and N-(aryl) maleimides, e.g.,N-phenyl maleimide, N-(C₁-C₉ linear or branched alkyl substitutedphenyl) maleimide, N-benzyl maleimide and N-(C₁-C₉ linear or branchedalkyl substituted benzyl) maleimide.

The oxirane functional monomer or its residue that is reacted with acarboxylic acid, may be selected from, for example, glycidyl(meth)acrylate, 3,4-epoxycyclohexylmethyl(meth)acrylate,2-(3,4-epoxycyclohexyl) ethyl(meth)acrylate, allyl glycidyl ether andmixtures thereof. Examples of carboxylic acids that may be reacted withthe oxirane functional monomer or its residue include, but are notlimited to, para-nitrobenzoic acid, hexanoic acid, 2-ethyl hexanoicacid, decanoic acid, undecanoic acid and mixtures thereof.

Other useful monomers include vinyl chloroacetate, isobutene,2-(2-bromopropionoxy) ethyl acrylate and (meth)acrylonitrile.

In the ATRP preparation of the copolymer, the amounts and relativeproportions of the initiator, the transition metal compound and theligand are those for which ATRP is most effectively performed. Theamount of initiator used can vary widely and is typically present in thereaction medium in a concentration of from 10⁻⁴ moles/liter (M) to 3M,for example, from 10⁻³M to 10⁻¹M. As the molecular weight of thecopolymer product can be directly related to the relative concentrationsof initiator and monomer(s), the molar ratio of initiator to monomer isan important factor in copolymer preparation. The molar ratio ofinitiator to monomer is typically within the range of 10⁻⁴:1 to 0.5:1,for example, 10⁻³:1 to 5×10⁻²:1.

In preparing the copolymer by ATRP methods, the molar ratio oftransition metal compound to initiator is typically in the range of10⁻⁴:1 to 10:1, for example, 0.1:1 to 5:1. The molar ratio of ligand totransition metal compound is typically within the range of 0.1:1 to100:1, for example, 0.2:1 to 10:1.

The copolymer may be prepared in the absence of solvent, i.e., by meansof a bulk polymerization process. Generally, the copolymer is preparedin the presence of a solvent, typically water and/or an organic solvent.Classes of useful organic solvents include, but are not limited to,esters of carboxylic acids, ethers, cyclic ethers, C₅-C₁₀ alkanes, C₅-C₈cycloalkanes, aromatic hydrocarbon solvents, halogenated hydrocarbonsolvents, amides, nitriles, sulfoxides, sulfones and mixtures thereof.Supercritical solvents, such as CO₂, C₁-C₄ alkanes and fluorocarbons,may also be employed. A preferred class of solvents are the aromatichydrocarbon solvents, particularly preferred examples of which arexylene, toluene and mixed aromatic solvents such as those commerciallyavailable from Exxon Chemical America under the trademark SOLVESSO.Additional solvents are described in further detail in U.S. Pat. No.5,807,937 at column 21, line 44 through column 22, line 54.

The ATRP preparation of the copolymer is typically conducted at areaction temperature within the range of 25° C. to 140° C., e.g., from50° C. to 100° C., and a pressure within the range of 1 to 100atmospheres, usually at ambient pressure. The ATRP is typicallycompleted in less than 24 hours, e.g., between 1 and 8 hours.

The ATRP transition metal catalyst and its associated ligand aretypically separated or removed from the copolymer product prior to itsuse, for instance, as an adhesion-promoting additive. Removal of theATRP catalyst may be achieved using known methods, including, forexample, adding a catalyst binding agent to the mixture of thecopolymer, solvent and catalyst, followed by filtering. Examples ofsuitable catalyst binding agents include, for example, alumina, silica,clay or a combination thereof. A mixture of the copolymer, solvent andATRP catalyst may be passed through a bed of catalyst binding agents.Alternatively, the ATRP catalyst may be oxidized in situ, the oxidizedresidue of the catalyst being retained in the polymer.

The copolymer can be a block copolymer having one or more segments. In atwo-segment copolymer, the copolymer may have the general formula IV:

φ-(A_(p)-B_(s)-X)_(t)  (IV)

where each of A and B in general formula IV may represent one or moretypes of monomer residues, while p and s represent the average totalnumber of A and B residues occurring per block or segment of A residues(A-block or A-segment) and B residues (B-block or B-segment),respectively, and t refers to the number of initiator sites present onthe initiator, φ. When containing more than one type or species ofmonomer residue, the A- and B-blocks may each have at least one ofrandom block, e.g., di-block and tri-block, alternating and gradientarchitectures. Gradient architecture refers to a sequence of differentmonomer residues that change gradually in a systematic and predictablemanner along the polymer backbone. For purposes of illustration, anA-block containing 6 residues of methyl methacrylate (MMA) and 6residues of ethyl methacrylate (EMA), for which p is 12, may havedi-block, tetra-block, alternating and gradient architectures asrepresented in general formulas V, VI, VII and VIII.

Di-Block Architecture

-(MMA-MMA-MMA-MMA-MMA-MMA-EMA-EMA-EMA-EMA-EMA-EMA)-  V

Tetra-Block Architecture

-(MMA-MMA-MMA-EMA-EMA-EMA-MMA-MMA-MMA-EMA-EMA-EMA)-  VI

 Alternating Architecture

-(MMA-EMA-MMA-EMA-MMA-EMA-MMA-EMA-MMA-EMA-MMA-EMA)-  VII

Gradient Architecture

-(MMA-MMA-MMA-EMA-MMA-MMA-EMA-EMA-MMA-EMA-EMA-EMA)-  VIII

The B-block may be described in a manner similar to that of the A-block.

The order in which monomer residues occur along the polymer backbone ofthe copolymer is typically determined by the order in which thecorresponding monomers are fed into the vessel in which the controlledradical polymerization is conducted. For example, in reference togeneral formula IV, the monomers that are incorporated as residues inthe A-block of the copolymer are generally fed into the reaction vesselprior to those monomers that are incorporated as residues in theB-block.

During formation of the A- and B-blocks, if more than one monomer is fedinto the reaction vessel at a time, the relative reactivities of themonomers typically determine the order in which they are incorporatedinto the living polymer chain. Gradient sequences of monomer residueswithin the A- and B-blocks can be prepared by controlled radicalpolymerization, and in particular by ATRP methods by (a) varying theratio of monomers fed to the reaction medium during the course of thepolymerization, (b) using a monomer feed containing monomers havingdifferent rates of polymerization, or (c) a combination of (a) and (b).Copolymers containing gradient architecture are described in furtherdetail in U.S. Pat. No. 5,807,937 at column 29, line 29 through column31, line 35.

Subscripts p and s represent average numbers of residues occurring inthe respective A- and B-blocks. Typically, subscript s has a value of atleast 1, and preferably at least 5 for general formula IV. Also,subscript s has a value of typically less than 300, preferably less than100, and more preferably less than 50, e.g., 20 or less, for generalformula IV. The value of subscript s may range between any combinationof these values, inclusive of the recited values, e.g., s may be anumber from 1 to 100. Subscript p may be 0, or may have a value of atleast 1, and preferably at least 5. Subscript p also typically has avalue of less than 300, preferably less than 100, and more preferablyless than 50, e.g., 20 or less. The value of subscript p may rangebetween any combination of these values, inclusive of the recitedvalues, e.g., p may be a number from 0 to 50.

The copolymer can have any suitable number average molecular weight(Mn). Suitable number average molecular weights can be from 5,000 to50,000, preferably from 12,000 to 40,000 most preferably from 17,000 to30,000, as determined by gel permeation chromatography using polystyrenestandards. The polydispersity index, i.e., weight average molecularweight (Mw) divided by Mn, of the graft portion of the copolymer istypically less than 2.0, e.g., less than 1.8 or less than 1.5.

Symbol φ of general formula I is, or is derived from, the residue of theinitiator used in the preparation of the copolymer by controlled radicalpolymerization, and is free of the radically transferable group (dormanthalide) of the initiator.

The symbol φ may also represent a derivative of the residue of theinitiator. For example, if the initiators have oxyranyl group-containingmoieties grafted thereto, the oxyranyl groups may be reacted eitherprior to or after the completion of the controlled radicalpolymerization with a carboxylic acid group-containing material. Classesof carboxylic acid group-containing materials with which oxyranylfunctional initiators or their residues may be reacted include, forexample, aromatic carboxylic acids, polycyclic aromatic carboxylicacids, aliphatic carboxylic acids having from 6 to 20 carbon atoms, andmixtures thereof. Specific examples of carboxylic acid group-containingmaterials with which oxyranyl functional initiators or their residuesmay be reacted may include, but are not limited to, para-nitrobenzoicacid, hexanoic acid, 2-ethyl hexanoic acid, decanoic acid, undecanoicacid and mixtures thereof.

In another embodiment of the present invention, a segment of thecopolymer, i.e., the —(A)_(p)— segment in general formula IV can serveas a linking segment between the hydrophobic residue of the initiator,i.e., φ- in general formula IV, and a hydrophilic segment, i.e., the—(B)_(s)— segment in general formula IV. In reference to general formulaIV, A may be a residue of C₁-C₄ alkyl (meth)acrylates. Examples of C₁-C₄alkyl (meth)acrylates of which A may be a residue include, methyl(meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl(meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate,tert-butyl (meth)acrylate and mixtures thereof.

Hydrophilic segments, i.e., —(B)_(s)— in reference to general formulaIV, may have nonionic moieties, ionic moieties and combinations thereof.The segment can comprise residues of a monomer selected from, forexample, poly(alkylene glycol) (meth)acrylates; C₁-C₄ alkoxypoly(alkylene glycol) (meth)acrylates; hydroxyalkyl (meth)acrylateshaving from 2 to 4 carbon atoms in the alkyl group; N-(hydroxy C₁-C₄alkyl) (meth)acrylamides (e.g., N-hydroxymethyl (meth)acrylamide andN-(2-hydroxyethyl) (meth)acrylamide); N,N-di-(hydroxy C₁-C₄ alkyl)(meth)acrylamides (e.g., N,N-di(2-hydroxyethyl) (meth)acrylamide);carboxylic acid functional monomers; salts of carboxylic acid functionalmonomers; amine functional monomers; salts of amine functional monomers;and mixtures thereof.

Hydrophilic segments including poly(alkylene glycol) (meth)acrylates andC₁-C₄ alkoxy poly(alkylene glycol) (meth)acrylates may be prepared byknown methods. For example, (meth)acrylic acid or hydroxyalkyl(meth)acrylate, e.g., 2-hydroxyethyl (meth)acrylate, may be reacted withone or more alkylene oxides, e.g., ethylene oxide, propylene oxide andbutylene oxide. Alternatively, an alkyl (meth)acrylate may betransesterified with a C₁-C₄ alkoxy poly(alkylene glycol), e.g., methoxypoly(ethylene glycol). Examples of preferred poly(alkylene glycol)(meth)acrylates and C₁-C₄ alkoxy poly(alkylene glycol) (meth)acrylatesinclude, poly(ethylene glycol) (meth)acrylate and methoxy poly(ethyleneglycol) (meth)acrylate, the poly(ethylene glycol) moiety of each havinga molecular weight of from 100 to 800. An example of a commerciallyavailable C₁-C₄ alkoxy poly(alkylene glycol) (meth)acrylate is methoxypoly(ethylene glycol) 550 methacrylate monomer from Sartomer Company,Inc.

A segment of the copolymer may include carboxylic acid functionalmonomers which include, but are not limited to, (meth)acrylic acid,maleic acid, fumaric acid and undecylenic acid. For instance, in generalformula IV, B may initially be a residue of a precursor of a carboxylicacid functional monomer that is converted to a carboxylic acid residueafter completion of the controlled radical polymerization, e.g., maleicanhydride, di(C₁-C₄ alkyl) maleates and C₁-C₄ alkyl (meth)acrylates. Forexample, residues of maleic anhydride can be converted to diacidresidues, ester/acid residues or amide/acid residues by art-recognizedreactions with water, alcohols or primary amines, respectively. Residuesof C₁-C₄ alkyl (meth)acrylates, such as t-butyl methacrylate, can beconverted to (meth)acrylic acid residues by art-recognized esterhydrolyzation methods, which typically involve the concurrent removal ofan alcohol, such as t-butanol by vacuum distillation. Salts ofcarboxylic acid functional monomers include, for example, salts of(meth)acrylic acid and primary, secondary or tertiary amines, such as,butyl amine, dimethyl amine and triethyl amine.

The copolymer may contain a segment that contains amine functionalmonomers which include, for example, amino(C₂-C₄ alkyl) (meth)acrylates,e.g., 2-aminoethyl (meth)acrylate, 3-aminopropyl (meth)acrylate and4-aminobutyl (meth)acrylate; N-(C₁-C₄ alkyl)amino(C₂-C₄ alkyl)(meth)acrylates, e.g., N-methyl-2-aminoethyl (meth)acrylate; andN,N-di(C₁-C₄ alkyl)amino(C₂-C₄ alkyl) (meth)acrylates, e.g.,N,N-dimethyl-2-aminoethyl (meth)acrylate. A segment may also compriseresidues of salts of amine functional monomers, e.g., salts of thoseamine functional monomers as recited previously herein. Salts of theamine functional monomer residues may be formed by mixing a carboxylicacid, e.g., lactic acid, with the copolymer after completion ofcontrolled radical polymerization.

In one embodiment of the copolymer, a segment contains carboxylic acidfunctional monomers selected from (meth)acrylic acid, maleic anhydride,maleic acid, di(C₁-C₄ alkyl) maleates, and mixtures thereof. In a stillfurther embodiment of the present invention, amine functional monomersare selected from amino(C₂-C₄ alkyl) (meth)acrylates, N-(C₁-C₄alkyl)amino(C₂-C₄ alkyl) (meth)acrylates, N,N-di(C₁-C₄ alkyl)amino(C₂-C₄alkyl) (meth)acrylates and mixtures thereof.

A segment of the copolymer may also contain cationic moieties selectedfrom ammonium, sulphonium and phosphonium. Ammonium, sulphonium andphosphonium moieties may be introduced into the graft copolymer by meansknown to the skilled artisan. For example, when a segment containsN,N-dimethyl-2-aminoethyl (meth)acrylate monomers, the N,N-dimethylaminomoieties may be converted to ammonium moieties by mixing an acid, e.g.,lactic acid, with the graft copolymer.

When a segment of the copolymer contains residues of oxirane functionalmonomers, such as glycidyl (meth)acrylate, the oxirane groups may beused to introduce sulphonium or phosphonium moieties into the copolymer.Sulphonium moieties may be introduced into the copolymer by reaction ofthe oxirane groups with thiodiethanol in the presence of an acid, suchas lactic acid. Reaction of the oxirane groups with a phosphine, e.g.,triphenyl phosphine or tributyl phosphine, in the presence of an acid,such as lactic acid, results in the introduction of phosphonium moietiesinto the copolymer.

Other reactive groups, such as carbamate groups, can be incorporatedinto the copolymer. Carbamate groups, may be introduced by including inthe ATRP reaction mixture monomers that include carbamate groups and/orby post-reacting the copolymer to add a carbamate group. For instance,carbamate functional groups can be incorporated into the copolymer byreacting a hydroxyl functional acrylic moiety with a low molecularweight alkyl carbamate such as methyl carbamate. Hydroxyl functionalacrylic moieties also can be reacted with isocyanic acid to providependant carbamate groups. Likewise, hydroxyl functional copolymers canbe reacted with urea to provide pendant carbamate groups.

In a preferred embodiment of the present invention, the radicallytransferable group is a halide group. Dormant halogens can be removedfrom the terminus of the graft copolymer by any manner known in the art,such as by HX abstraction. Typically the dormant halogen is removed bymeans of a mild dehalogenation reaction, that typically is performed asa post-reaction after the graft copolymer has been formed, and in thepresence of at least an ATRP catalyst. Preferably, the dehalogenation isperformed in the presence of both an ATRP catalyst and its associatedligand.

As discussed above, the ATRP process can be conducted with a sequence ofmonomers to produce a defined copolymer. Thus, the choice of monomersand the sequence of their reaction with dormant halide groups of theinitiator and/or propagating chain will influence the final structure ofthe copolymer. The choice of macroinitiator also will dictate thephysical structure of the copolymer. For instance, initiation withcertain dormant halides will be more favorable than others. The degreeof branching of the macroinitiator also will affect the final structureof the copolymer. Since the dormant halide groups of the macroinitiatorare pendant, grafted linear portions of the polyolefin backbone willhave a comb-like structure. Macroinitiators with branched structureswill yield a more complex, branched copolymer with both comb-likesections, corresponding to relatively linear portions of the backbone,and star-like sections that are the result of grafting onto a tertiarycarbon at a branch point between linear portions of the polyolefinbackbone. The average weight of the macroinitiator also will dictate thecomplexity of the resultant copolymer. Lastly, the number of dormanthalides on the polyolefin backbone, i.e., the weight percent of activehalide groups in the initiator, will effect the structure of thecopolymer.

The copolymer prepared according to the methods of the present inventionis a copolymer having a polyolefinic backbone and one or more polymerblocks prepared according to the above-described process.

Thus, the copolymer of the present invention includes a polyolefinbackbone with pendant halide groups and pendant polymeric blocks ofradically polymerizable alkenes containing a polar group that areattached to tertiary carbons of the backbone. The blocks may be of thesame monomer, but preferably are of two or more different monomers. Theblocks may be homopolymeric or copolymeric. The blocks typically areattached sequentially to the polyolefin backbone, as in generalstructure (IX):

PO—(A—B—X)_(n)  (IX)

Where PO is the backbone, n is an integer greater than 0, A is a firstblock of monomers, B is a second block of monomers and X is a dormanthalide. The monomer content of each of block A and B differ. By “monomercontent” it is meant both the type of monomer, i.e., GMA vs. MMA, andthe relative ratio of the monomers, by weight, in each block. It shouldbe noted that in certain circumstances, even though blocks of A areattached directly to the backbone, blocks of B may also be attacheddirectly to the backbone. This can result from the incomplete use ofdormant halides on the backbone. In such a case, at least three types ofgrafts exist, according to the following: —A—X. —A—B—X and —B—X, each ofwhich may exist on the same or different backbone. The relative amountof each of these grafts will depend on the reaction conditions andstructure of the initiator, and is dependent upon the relativeinitiation and propagation contents for the respective dormant halidesand monomers chosen under the specific reaction conditions.

In one embodiment of the present invention, the copolymer is used as anadditive for a film-forming composition. The additive promotes adhesionof the film-forming composition to a polyolefinic substrate, therebypreventing delamination of the film-forming composition from thesubstrate.

The copolymer typically is present in the film-forming composition in anamount of at least 1.5% by weight, preferably at least 3% by weight, andmore preferably at least 5% by weight, based on the total weight of theresin solids other than the copolymer in the film-forming composition.The copolymer is also typically present in the film-forming compositionin an amount of less than 20% by weight, preferably less than 5% byweight, and more preferably less than 3% by weight, based on the totalweight of the resin solids in the film-forming composition. The amountof copolymer present in the film-forming composition of the presentinvention may range between any combination of these values, inclusiveof the recited values.

Nevertheless, depending upon the structure of the copolymer, and theactive groups present thereon, the copolymer can serve as a primaryfilm-forming resin in a coating. In this particular embodiment, thegraft copolymer is typically present in the film forming composition inan amount of about 50% to 100% by weight, preferably 45% to 100% byweight.

A crosslinking agent typically is present in the film-formingcomposition. Generally, the crosslinking agent is an aminoplast or anisocyanate. An aminoplast crosslinking agent is commonly a partially orfully alkylated aminoplast crosslinking agent. The aminoplastcrosslinking agent can have a plurality of functional groups, forexample, alkylated methylol groups, that are reactive with the pendantcarbamate groups present in the acrylic, polyester, polyurethane orpolyether polymer.

Aminoplast resins, which include phenoplasts, as curing agents forhydroxyl, carboxylic acid and carbamate functional group-containingmaterials are well-known in the art. Aminoplast crosslinking agents areobtained from the reaction of formaldehyde with an amine and/or anamide. Melamine, urea, or benzoguanamine condensates are preferred.However, aminoplast condensates prepared from other amines or amides canbe used, for example, aldehyde condensates of glycouril, which areuseful in formulating powder coatings. Most often, formaldehyde is usedas the aldehyde; however, other aldehydes such as acetaldehyde,crotonaldehyde, and benzaldehyde are also suitable.

By the term “fully alkylated” it is meant that the alkylol groupsassociated with the reaction product of an aldehyde with an amine and/oran amide have been etherified to an extent that the alkoxy groups makeup at least 80% by weight of the functional groups.

A preferred aminoplast crosslinking agent is a melamine-formaldehydecondensate that has been fully alkylated, that is, themelamine-formaldehyde condensate contains methylol groups that have beenfurther etherified with an alcohol, preferably one that contains 1 to 6carbon atoms. Any monohydric alcohol can be employed for this purpose,including methanol, ethanol, n-butanol, isobutanol, and cyclohexanol.Most preferably, a blend of methanol and n-butanol is used. Suitableaminoplast resins are commercially available from Cytec Industries, Inc.under the trademark CYMEL® and from Solutia, Inc. under the trade nameRESIMENE®.

The aminoplast curing agent is typically present in the compositions ofthe invention in an amount ranging from 2 to 60 wt. %, preferably from10 to 50 wt. %, and more preferably from 15 to 45 wt. % based on thetotal weight of resin solids in the composition.

The curing agent may also be a polyisocyanate that optionally can beadded as an adjuvant curing agent, along with an aminoplast. As usedherein and in the claims, the term “polyisocyanatel” is intended toinclude blocked (or capped) polyisocyanates as well as unblockedpolyisocyanates. The polyisocyanate can be an aliphatic or an aromaticpolyisocyanate or a mixture of the two. Diisocyanates may be used,although higher polyisocyanates such as isocyanurates of diisocyanatesare preferred. Higher polyisocyanates can also be used in combinationwith diisocyanates. Isocyanate prepolymers, for example, reactionproducts of polyisocyanates with polyols, can also be used. Mixtures ofpolyisocyanate curing agents can be used.

Examples of suitable aliphatic diisocyanates are straight-chainaliphatic diisocyanates such as 1,4-tetramethylene diisocyanate and1,6-hexamethylene diisocyanate. Also, cycloaliphatic diisocyanates canbe employed. Examples include isophorone diisocyanate and4,4′-methylene-bis(cyclohexyl isocyanate). Examples of suitable aromaticdiisocyanates are p-phenylene diisocyanate,diphenylmethane-4,4′-diisocyanate and 2,4- or 2,6-toluene diisocyanate.Other diisocyanates include 1,3-bis(1-isocyanato-1-methylethyl)benzene.Examples of suitable higher polyisocyanates aretriphenylmethane-4,4′,4″-triisocyanate, 1,2,4-benzene triisocyanate andpolymethylene polyphenyl isocyanate. Other polyisocyanates includebiurets and isocyanurates of diisocyanates, including mixtures thereof,such as the isocyanurate of hexamethylene diisocyanate, the biuret ofhexamethylene diisocyanate, and the isocyanurate of isophoronediisocyanate. Isocyanate prepolymers, for example, reaction products ofpolyisocyanates with polyols such as neopentyl glycol and trimethylolpropane or with polymeric polyols such as polycaprolactone diols andtriols (NCO/OH equivalent ratio greater than one), can also be used.

If the polyisocyanate is blocked or capped, any suitable aliphatic,cycloaliphatic, or aromatic alkyl monoalcohol known to those skilled inthe art can be used as a capping agent for the polyisocyanate including,for example, lower aliphatic alcohols such as methanol, ethanol, andn-butanol; cycloaliphatic alcohols such as cyclohexanol; aromatic-alkylalcohols such as phenyl carbinol and methylphenyl carbinol; and phenoliccompounds such as phenol itself and substituted phenols wherein thesubstituents do not affect coating operations, such as cresol andnitrophenol.

Glycol ethers may also be used as capping agents. Suitable glycol ethersinclude ethylene glycol butyl ether, diethylene glycol butyl ether,ethylene glycol methyl ether and propylene glycol methyl ether. Othersuitable capping agents include oximes, pyrazoles and lactams. Oneparticular example is isophorone diisocyanate capped with methyl ethylketoxime.

When used, the polyisocyanate curing agent is present in an amountranging from 1 to 40 wt. %, preferably from 1 to 20 wt. %, morepreferably 1 to 10 wt. % based on the total weight of resin solids inthe film-forming composition.

Examples of other blocked polyisocyanates include triazine compoundshaving the formula C₃N₃(NHCOXR)₃, wherein X is nitrogen, oxygen, sulfur,phosphorus, or carbon, and R is an alkyl group having one to twelve,preferably one to four, carbon atoms, or mixtures of such alkyl groups.X is preferably oxygen or carbon, more preferably oxygen. R preferablyhas one to eight carbon atoms, for example, methyl, ethyl, n-propyl,isopropyl, butyl, n-octyl and 2-ethylhexyl. R is preferably a mixture ofmethyl and butyl groups. Such compounds, and the preparation thereof,are described in detail throughout U.S. Pat. No. 5,084,541, incorporatedherein by reference. Examples of triazine compounds are tris carbamoyltriazine or 1,2,5 triazine-2,4,6 tris-carbamic acid esters. When used,the triazine curing agent is present in the film-forming composition inan amount ranging from 1 to 40 wt. %, preferably from 1 to 20 wt. %,more preferably 1 to 10 wt. % based on the total weight of resin solidsin the film-forming composition.

Optionally, a diluent can be present in the film-forming composition,that serves to reduce the viscosity of the coating composition. If thecoating composition is solvent-borne, the diluent typically comprises anorganic solvent. Examples of suitable solvents include alcohols such asethanol, isopropanol, n-butanol, and the like; esters such as n-butylacetate, n-hexyl acetate, pentyl propionate, and the like; ethers suchas the monoethyl, monobutyl and monohexyl ethers of ethylene glycol andpropylene glycol, and the like; ketones such as methyl ethyl ketone,methyl isobutyl ketone, diisobutyl ketone, and the like; aromatichydrocarbons such as xylene, or toluene, and the like; aliphatic oralicyclic hydrocarbons such as the various petroleum naphthas andcyclohexane; and mixtures thereof.

When present, diluents are typically used at a level of up to about 97%by weight based on the total weight of the film-forming composition.

The film-forming composition can also be used in particulate form, i.e.,as a powder coating, in which the acrylic polymer and the oligomer orpolymer containing the repeating ester groups are chosen such that theyhave a glass transition temperature (Tg) greater than 60° C. Thesematerials can then be combined with an aldehyde condensate of glycouril,as previously mentioned, to form a powder film-forming composition.

The film-forming composition is typically a thermosetting compositionand typically contains catalysts to accelerate the curing reactions.Typically, the catalysts are acidic materials. Sulfonic acids,substituted sulfonic acids and amine neutralized sulfonic acids arepreferred, for example, p-toluene sulfonic acid, dodecyl benzenesulfonic acid, dinonylnaphthalene disulfonic acid, and the like. Thecatalyst is usually present in an amount of from 0.3 to 5.0 percent,preferably from 0.5 to 1.0 percent, the percentages based on the totalweight of resin solids in the coating composition.

The film-forming composition can contain other optional ingredients,such as co-reactive resinous materials, plasticizers, anti-oxidants, UVlight absorbers, surfactants, flow control agents, anti-settling agents,and the like. When present, these materials are generally used at alevel of less than 25%, preferably less than 10% by weight, thepercentages based on the total weight of resin solids in the coatingcomposition. The coating composition can also contain pigment.

The film-forming composition containing additive quantities of thecopolymer is applied to a polyolefinic substrate directly. However,since the physical characteristics of the copolymer of the presentinvention can vary broadly, the copolymer may be present in othercoating layers or can find use for purposes other than promotingadhesion to a polyolefinic substrate. In that case, the coating can beapplied to any of the various substrates to which it adheres. Specificexamples of suitable substrates include metals, wood, glass, cloth,plastic, foam, elastomeric substrates, and the like. Typically, thesubstrate is metal or plastic and, most typically, a polyolefinicplastic. Optionally, the substrate could have been previously coatedwith an electrocoat primer and/or a primer surfacer and/or a pigmentedbasecoat and the film-forming composition of the present inventionapplied as a clear coat over the pigmented base coat to form a colorplus clear composite coating.

The compositions can be applied by conventional means includingbrushing, dipping, flow coating, spraying, and the like. Preferably,they are applied by spraying. The usual spray techniques and equipmentfor air-spraying or electrostatic spraying can be used.

The copolymers of the present invention find use in many fields, such asin coating compositions, compositions for molding, extruding and otherarticle fabrication processes, healthcare and personal care compositionsand in any other application for polymeric compounds.

The present invention is more particularly described in the followingexamples, which are intended to be illustrative only, since numerousmodifications and variations therein will be apparent to those skilledin the art. Unless otherwise specified, all parts and percentages are byweight.

A. SYNTHESIS EXAMPLES Example 1 Synthesis of Graft Copolymer ChlorinatedPolyolefin (CPO)-GMA-MMA

Glycidyl methacrylate (GMA) and methyl methacrylate (MMA) residues werecopolymerized using a CPO initiator according to the following:

TABLE A Ingredients Parts by weight (grams) Charge 1 Xylene 588.90Copper 0.64 2,2′-Bypyridyl 1.09 Magnesol¹ 20 CP343-1 CPO² 250 (solid)GMA 42.60 Charge 2 MMA 100 ¹A hydrated, synthetic, amorphous form ofmagnesium silicate, commercially available from The Dallas Group ofAmerica, Inc. ²A maleic anhydride-modified chlorinated polypropylenehaving a chloride content of 18% to 23% by weight, commerciallyavailable from Eastman Chemical Company.

Charge 1 was heated in a reaction vessel with agitation at 85° C. andthe reaction mixture was held at this temperature for 2 hours. Thecharge 2 was added over a period of 15 minutes. The reaction mixture washeld at 85° C. for 3 hours. The reaction mixture was cooled andfiltered. The resultant graft copolymer had a total solid content of41.3% determined at 110° C. for one hour. The copolymer had numberaverage molecular weight, Mn=20,320 and polydispersity Mw/Mn=2.57(determined by gel permeation chromatography using polystyrene as astandard). The chlorinated polyolefin (CP343-1) macroinitiator hadnumber average molecular weight, Mn=13,950 and polydispersity Mw/Mn=2.20(determined by gel permeation chromatography using polystyrene as astandard). The ¹H NMR spectrum is fully consistent with graft-copolymerCPO-GMA-MMA, exhibiting all key absorption of monomers used and the peakarising from macroinitiator. DSC data show for the graft copolymeryielded a melting point of Tm=98° C., and percentage of crystallinityWc˜1%.

Example 2 Synthesis of Graft Copolymer Chlorinated Polyolefin(CPO)-GMA/Neodecanoic Acid-MMA

An adduct of GMA and neodecanoic acid (GMA/neodecanoic acid) and MMAresidues were copolymerized using a CPO initiator according to thefollowing:

TABLE B Ingredients Parts by weight (grams) Charge 1 Xylene 588.9 Copper(II) bromide 0.11 Copper 0.06 2,2′-Bypyridyl 0.11 Magnesol 20 CP343-1CPO 250 GMA/Neodecanoic acid¹ 94.82 Charge 2 MMA 100 ¹An adduct ofGMA/neodecanoic acid.

Charge 1 was heated in a reaction vessel with agitation at 85° C. andthe reaction mixture was held at this temperature for 2 hours. Thecharge 2 was added over a period of 15 minutes. The reaction mixture washeld at 85° C. for 3 hours. The reaction mixture was cooled andfiltered. The resultant graft copolymer had a total solid content of44.2% determined at 110° C. for one hour. The copolymer had numberaverage molecular weight, Mn=15,790 and polydispersity Mw/Mn=2.79(determined by gel permeation chromatography using polystyrene as astandard). The chlorinated polyolefin (CP343-1) macroinitiator hadnumber average molecular weight, Mn=13,950 and polydispersity Mw/Mn=2.20(determined by gel permeation chromatography using polystyrene as astandard). The ¹H NMR spectrum is fully consistent with graft-copolymerCPO-GMA/neodecanoic acid-MMA, exhibiting all key absorption of monomersused and the peak arising from macroinitiator. DSC data show for thegraft copolymer yielded a melting point of Tm=87° C., and percentage ofcrystallinity Wc˜4%.

Example 3 Synthesis of Graft Copolymer Chlorinated Polyolefin(CPO)-HPMA-MMA-HPMA

Hydroxypropyl methacrylate (HPMA) and MMA residues were copolymerizedusing a CPO initiator according to the following:

TABLE C Ingredients Parts by weight (grams) Charge 1 Xylene 588.9 Copper(II) bromide 0.67 Copper 0.06 2,2′-Bypyridyl 0.11 Magnesol 20 CP343-1CPO 250 HPMA 21.60 Charge 2 MMA 100 Charge 3 HPMA 21.30

Charge 1 was heated in a reaction vessel with agitation at 85° C. andthe reaction mixture was held at this temperature for 2 hours. Thecharge 2 was added over a period of 15 minutes. The reaction mixture washeld at 85° C. for 3 hours. The charge 3 was added over a period of 15minutes. The reaction mixture was held at 85° C. for 2 hours. Thereaction mixture was cooled and filtered. The resultant graft copolymerhad a total solid content of 41.0% determined at 110° C. for one hour.The copolymer had number average molecular weight, Mn=19,640 andpolydispersity Mw/Mn=3.0 (determined by gel permeation chromatographyusing polystyrene as a standard). The chlorinated polyolefin (CP343-1)macroinitiator had number average molecular weight, Mn=15,120 andpolydispersity Mw/Mn=2.30 (determined by gel permeation chromatographyusing polystyrene as a standard). The ¹H NMR spectrum is fullyconsistent with graft-copolymer CPO-HPMA-MMA-HPMA, exhibiting all keyabsorption of monomers used and the peak arising from macroinitiator.DSC data show for the graft copolymer yielded a melting point of Tm=91°C., and percentage of crystallinity Wc˜3%.

Example 4 Synthesis of Graft Copolymer Chlorinated Polyolefin (CPO)-HPMA

HPMA residues were polymerized using a CPO initiator according to thefollowing:

TABLE D Ingredients Parts by weight (grams) Charge 1 Xylene 1177.80Copper (II) bromide 1.34 Copper 0.34 2,2′-Bypyridyl 0.44 Magnesol 40CP343-1 CPO 500 HPMA 285.80

Charge 1 was heated in a reaction vessel with agitation at 85° C. andthe reaction mixture was held at this temperature for 4 hours. Thereaction mixture was cooled and filtered. The resultant graft copolymerhad a total solid content of 41.3% determined at 110° C. for one hour.The copolymer had number average molecular weight, Mn=20,380 andpolydispersity Mw/Mn=3.0 (determined by gel permeation chromatographyusing polystyrene as a standard). The chlorinated polyolefin (CP343-1)macroinitiator had number average molecular weight, Mn=15,120 andpolydispersity Mw/Mn=2.30 (determined by gel permeation chromatographyusing polystyrene as a standard). The ¹H NMR spectrum is fullyconsistent with graft-copolymer CPO-HPMA, exhibiting all key absorptionof monomer used and the peak arising from macroinitiator. DSC data showfor the graft copolymer yielded a melting point of Tm=87° C., andpercentage of crystallinity Wc˜2%.

Example 5 Synthesis of Graft Copolymer Chlorinated Polyolefin(CPO)-HPMA-MAA/Cardura E-HPMA

HPMA and an adduct of Cardura E and methacrylic acid (MAA/Cardura E)were copolymerized using a CPO initiator according to the following:

TABLE E Ingredients Parts by weight (grams) Charge 1 Xylene 422.6Cardura E 100 Copper 0.75 2,2′-Bypyridyl 2.5 CP343-1 CPO 250 HPMA 28.80Charge 2 MAA/Cardura E¹ 135.20 Charge 3 HPMA 43.20 ¹An adduct ofMMA/Cardura E.

Charge 1 was heated in a reaction vessel with agitation at 80° C. andthe reaction mixture was held at this temperature for 1 hour. The charge2 was added over a period of 15 minutes. The reaction mixture was heldat 80° C. for 3 hours. The charge 3 was added over a period of 15minutes. The reaction mixture was held at 85° C. for 3 hours. Thereaction mixture was cooled and filtered. The resultant graft copolymerhad a total solid content of 46.6% determined at 110° C. for one hour.The copolymer had number average molecular weight, Mn=21,660 andpolydispersity Mw/Mn=3.0 (determined by gel permeation chromatographyusing polystyrene as a standard). The chlorinated polyolefin (CP343-1)macroinitiator had number average molecular weight, Mn=15,120 andpolydispersity Mw/Mn=2.30 (determined by gel permeation chromatographyusing polystyrene as a standard). The ¹H NMR spectrum is fullyconsistent with graft-copolymer CPO-HPMA-MAA/Cardura E-HPMA, exhibitingall key absorption of monomers used and the peak arising frommacroinitiator.

B. COATING EXAMPLES Example 6 Use of the Resin of Example 5 in anAdhesion Promoting Coating Layer

The resin of Example 5 was evaluated as a low solids, direct substrateadhesion promoter (Coating A). Adhesion to various substrates wascompared to the CPO precursor material (Coating B), and a commercialadhesion promoter (DPX-801, PPG Industries, Inc.) (Coating C).

TABLE F Coating A Coating B Component weight (g) weight (g) Resin ofExample 5 19.9 — CP343-1 CPO — 12.5 Xylene 80.1 87.5 Total 100.0  100.0 

Plastic substrates were cleaned and abraded using water, an abrasivedetergent (DX101, PPG Industries, Inc.), and an abrasive pad (grayScotch-Brite™, 3M). After rinsing with water and subsequent drying, thesubstrates were wiped with two additional solvent-based cleaners (DX330,PPG Industries, Inc., DX103 PPG Industries, Inc.).

Coatings A, B, and C were applied directly to the cleaned plasticsubstrates (˜0.1-0.2 DFT), followed by primer sealer (K36, PPGIndustries, Inc.), basecoat (DBC4037, PPG Industries, Inc.), andclearcoat (DCU2042, PPG Industries, Inc., coating layers. Coatedsubstrates were cured at ambient temperature.

Coating adhesion was evaluated using a Crosshatch adhesion test. Using amulti-blade cutter (Paul N. Gardner Company, Inc.), coated panels werescribed twice (at 90°), making sure the blades cut through all coatinglayers into the substrate. Coating adhesion was measured using NichibanL-24 tape (four pulls at 90°). Adhesion was rated on a 0-5 scale (5=100%adhesion, 0=0% adhesion). Failure mode was adhesive between thesubstrate and adhesion promoter, unless otherwise noted in the results.

Adhesion measurements were taken one and seven days after application.Additional samples were aged for seven days, then exposed to elevatedtemperature and humidity (100° C./100% for four days). Adhesion wasevaluated immediately and one day after exposure. Adhesion results aresummarized in Table G below. Grafting to the CPO (as in Example 5) doesnot negatively effect adhesion to the various plastic substrates.Additionally, performance of the resin of Example 5 is similar to thecommercial adhesion promoter.

TABLE G Adhesion Adhesion Adhesion Adhesion 1 Hour after 1 Day after 1Day 7 Day Exposure² Exposure² Substrate¹ (0-5) (0-5) (0-5) (0-5) CoatingBayflex 4 4 4 4 A 110-35 Sequel 4 4 4 4 1440 Montell 4 4 4 4 CA186TSOP-1 4 4 4 4 Himont 5 5 5 4 SD242 Coating Bayflex 4 4 4 4 B 110-35Sequel 4 4 4 4 1440 Montell 4 4 4 4 CA186 TSOP-1 4 4 4 4 Himont 5 4 5 3SD242 Coating Bayflex 4 4 4 4 C 110-35 Sequel 4 4 4 4 1440 Montell 4 4 44 CA186 TSOP-1 4 4 4 4 Himont 5 5 5 4 SD242 ¹All panels were purchasedfrom ACT Laboratories, Inc. ²100° F./100% humidity, 4 days.

Example 7 Use of the Polymer of Example 5 as an Adhesion-PromotingIngredient in a Primer-Sealer—Comparison to Commercially AvailableAdhesion-Promoting Layer

The resin of Example 5 was evaluated as an adhesion-promoting ingredientin a primer sealer for plastic substrates (Coating D). Pigmentation wasdispersed into the resin of Example 5 by milling.

TABLE H Coating D Component weight (g) Resin of Example 5 214.4Disperbyk-110¹ 5.5 Talc Pigment 25.0 TiO₂ Pigment 25.0 Barium Sulfate25.0 Pigment Black Tint Paste 1.0 Toluene 101.1 Butyl acetate 103.0Total 500.0 ¹A wetting and dispersing additive, commercially availablefrom Byk Chemie.

Plastic substrates were cleaned as described in Example 6. Coating D wasapplied directly to the various plastic substrates, followed by basecoat(DBC4037, PPG Industries, Inc.) and clearcoat (DCU2042, PPG Industries,Inc.) coating layers. Additionally, a commercial system was evaluated.Adhesion promoter (Coating E) (DPX-801, PPG Industries, Inc.) wasapplied directly to the cleaned substrates, followed by primer sealer(K36, PPG Industries, Inc.), basecoat (DBC4037, PPG Industries, Inc.),and clearcoat (DCU2042, PPG Industries, Inc.) coating layers. Coatedsubstrates were cured at ambient temperature.

Coating adhesion was tested as described in Example 6. The results inTable I indicate that primer sealer prepared from the resin of Example 5(Coating D) provides similar adhesion to the commercial system (CoatingE), without use of a separate adhesion promoter layer.

TABLE I Adhesion Adhesion Adhesion Adhesion 1 Hour after 1 Day after 1Day 7 Day Exposure² Exposure² Substrate¹ (0-5) (0-5) (0-5) (0-5) CoatingBayflex  3³ 4 4 4 D 110-35 Sequel 4 4 4 4 1440 Montell 4 4 4 4 CA186TSOP-1 4 4 4 4 Himont  3³ 5 4 4 SD242 Coating Bayflex 4 4 4 4 E 110-35Sequel 4 4 4 4 1440 Montell 4 4 4 4 CA186 TSOP-1 4 4 4 4 Himont 4 4 4 4SD242 ¹All panels purchased from ACT Laboratories, Inc. ²100° F./100%humidity, 4 days. ³Primer sealer/basecoat adhesive failure.

Example 8 Use of the Resin of Example 5 as an Adhesion-PromotingAdditive for a Primer-Sealer

The resin of Example 5 was evaluated as an adhesion-promoting additivefor an existing primer sealer system. Experimental coatings wereformulated containing 0, 5, 10 or 20 wt. % CPO based on resin solids.

TABLE J Coating F Coating G Coating H Coating I Component Weight (g)weight (g) weight (g) weight (g) K36 Prima¹ 99.8 99.8 99.8 99.8 DCU2021²31.7 23.4 15.0 — Resin of — 19.0 38.0 72.0 Example 5 Xylene — 30.0 25.035.0 DT870³ 27.6 — — — DCX8⁴ 17.9 17.9 17.9 17.9 Total 177.0  190.1 195.7  224.7  ¹K36 Prima (primer), commercially available from PPGIndustries, Inc. ²DCU2021 (clearcoat), commercially available from PPGIndustries, Inc. ³DT870 (reducing solvent), commercially available fromPPG Industries, Inc. ⁴DCX8 (isocyanate hardener), commercially availablefrom PPG Industries, Inc.

Coatings F-I were applied directly to cleaned plastic substrates (seeExample 6), followed by basecoat (DBC4037, PPG Industries, Inc.) andclearcoat (DCU2042, PPG Industries, Inc.) layers. Additionally, aCoating J was prepared, wherein the cleaned substrate was coated with acommercial adhesion promoter (DPX-801, PPG Industries, Inc.), a primersealer (K36, PPG Industries, Inc.), a basecoat (DBC4037, PPG Industries,Inc.), and a clearcoat (DCU2042, PPG Industries, Inc.). All coatedsubstrates were cured at ambient temperature. The adhesion properties ofthe coatings are summarized in Table K.

TABLE K Adhesion Adhesion Coating Adhesion Adhesion 1 Hour after 1 Dayafter Exam- 1 Day 7 Day Exposure² Exposure² ple Substrate¹ (0-5) (0-5)(0-5) (0-5) Coating Bayflex 4 4 3 3 F 110-35 Sequel 0 0 0 0 1440 Montell0 0 0 0 CA186 TSOP-1 1 0 0 0 Himont 0 0 0 0 SD242 Coating Bayflex 4 4 33 G 110-35 Sequel 3 3 4 2 1440 Montell 4 3 4 3 CA186 TSOP-1 4 3 4 3Himont 4 4 3 0 SD242 Coating Bayflex 4 4 3 4 H 110-35 Sequel 4 4 4 31440 Montell 4 3 4 3 CA186 TSOP-1 4 4 4 3 Himont 4 4 4 4 SD242 CoatingBayflex 4 4 3 3 I 110-35 Sequel 4 4 4 2 1440 Montell 4 3 3 3 CA186TSOP-1 4 4 4 3 Himont 4 4 4 3 SD242 Coating Bayflex 4 4 3 3 J 110-35Sequel 4 3 4 3 1440 Montell 4 3 4 3 CA186 TSOP-1 4 3 4 3 Himont 4 4 4 3SD242 ¹All panels purchased from ACT Laboratories, Inc. ²100° F./100%humidity, 4 days.

The data in Table K demonstrate that the copolymer of the presentinvention is comparable to commercially available adhesion promoters inits adhesion promoting activities.

C. Comparison of ATRP Using a CPO Initiator vs. a Conventional FreeRadical Polymerization Process

For comparison of the process for the present invention and U.S. Pat.No. 5,955,545, copolymers were prepared according to the process of thepresent invention (Example 9) and U.S. Pat. No. 5,955,545 (Example 10).

Example 9 Synthesis by ATRP of Graft Copolymer CPO-CHMA/BMA/IBMA/HPMA

Cyclohexyl methacrylate (CHMA), butyl methacrylate (BMA), isobutylmethacrylate (IBMA) and HPMA were copolymerized using a CPO initiatoraccording to the following:

TABLE L Ingredients Parts by weight (grams) Charge 1 Xylene 100.00Copper 0.60 2,2′-Bypyridyl 2.00 Cardura E 30.00 CP515-2 CPO¹ 195.3 (40%TS in xylene) CHMA 150.00 BMA 52.50 IBMA 70.00 HPMA 285.80 ¹Achlorinated polypropylene with 26% to 32% chlorine by weight (notmodified with maleic anhydride), commercially available from EastmanChemical Company.

Charge 1 was heated in a reaction vessel with agitation at 85° C. andthe reaction mixture was held at this temperature for seven hours. Thereaction mixture was cooled and filtered. The resultant graft copolymerhad a total solid content of 61.7% determined at 110° C. for one hour.The copolymer had number average molecular weight, Mn=39735 andpolydispersity Mw/Mn=3.0 (determined by gel permeation chromatographyusing polystyrene as a standard). The chlorinated polyolefin (CP515-2)macroinitiator had number average molecular weight, Mn=19390 andpolydispersity Mw/Mn=2.30 (determined by gel permeation chromatographyusing polystyrene as a standard). The 1H NMR spectrum is fullyconsistent with graft-copolymer CPO-CHMA/BMA/IBMA/HPMA, exhibiting allkey absorption of monomers used and the peak arising from themacroinitiator. DSC data show for graft copolymer a glass transitiontemperature Tg=24° C. (CP 515-2 had Tg=0.7° C.).

Example 10 Synthesis by Free Radical Polymerization of CopolymerCPO/CHMA/BMA/IBMA/HPMA

CHMA, BMA, IBMA and HPMA residues were copolymerized using a halogenatedCPO initiator according to the following:

TABLE M Ingredients Parts by weight (grams) Charge 1 Xylene 100.00CP515-2 CPO 195.3 (40% TS in xylene) Charge 2 VAZO 64¹ 1.00 CHMA 150.00BMA 52.50 IBMA 70.00 HPMA 285.80 Charge 3 VAZO 64 1.00¹Azobisisobutyronitrile, commercially available from E.I. duPont deNemours and Company.

Charge 1 was heated in a reaction vessel with agitation at 100° C. andto the reaction mixture was added charge 2 over a two hour period. Atthe end of the feed, the temperature was dropped to 80° C., and thancharge 3 was added. The reaction mixture was held for five hours at 80°C. The reaction mixture was cooled and filtered. The resultant graftcopolymer had a total solid content of 61.7% determined at 110° C. forone hour. The copolymer had number average molecular weight, Mn=19790and polydispersity Mw/Mn=2.6 (determined by gel permeationchromatography using polystyrene as a standard). The chlorinatedpolyolefin (CPS15-2) macroinitiator had number average molecular weight,Mn=19390 and polydispersity Mw/Mn=2.30 (determined by gel permeationchromatography using polystyrene as a standard). The 1H NMR spectrum isfully consistent with copolymer CPO/CHMA/BMA/IBMA/HPMA, exhibiting allkey absorption of monomers used and the peak arising from themacroinitiator. DSC data show for graft copolymer a glass transitiontemperature Tg=37.1° C. (CP 515-2 had Tg=0.70° C.), which differs fromthe Tg of the resin of Example 9 (24° C.).

Example 11 Comparison of Resin of Examples 9 and 10 to CPO asAdhesion-Promoting Layer

Physical properties of the resins of Examples 9 and 10, as well as theprecursor CPO material, were characterized using several test methods.Results, as well as a description of the test methods, are summarized inTable N. Physical properties clearly indicate that the twopolymerization methods result in two distinct polymers, with uniquechain architectures. Adhesion promoting compositions prepared usingresins prepared according to U.S. Pat. No. 5,955,545 (Example 10) wereless stable and hazy, indicating incompatibility.

The resins of Examples 9 and 10, as well as the CPO precursor material,were formulated as low solids, direct-to-substrate adhesion promoters(Coatings K-M in Table O). Plastic substrates were prepared as outlinedin Example 6. Coatings K-M, as well as a commercial adhesion promoter(Coating N, in Table P) (DPX-801, PPG Industries, Inc.), were applied tothe cleaned substrates (˜0.1-0.2 mil DFT). Subsequently, substrates werecoated with primer sealer (K36, PPG Industries, Inc.), basecoat (DBC4037, PPG Industries, Inc.), and clearcoat (DCU 2042, PPG Industries,Inc.) coating layers. Coated substrates were cured at ambienttemperature.

Coating adhesion was evaluated as described in Example 6. Results aresummarized in Table P.

TABLE N Solid Resin Appearance Solids Equiv. Viscosity² of ResinAppearance of Stability⁶ Tg⁷ Resin (%) Weight¹ (cps) Mn³ Solution SolidFilm 39° F./120° F. (° C.) CPO 40 (theory) NA 38 19390 Visual: Visual:Clear Pass/Pass −0.7 Precursor Slightly UV/Vis. (Eastman CloudyExtinction⁵: 1 515-2) Resin of 61.8 1500 63 39730 Visual: Visual: ClearPass/Pass 24.0 Example 9 (synthesis) (theory) Clear UV/Vis. 1351 Haze⁴:18.63 Extinction⁵: <1 (actual) Resin of 68.6 1400 45 19730 Visual:Visual: Cloudy Fail (cloudy, 37.1 Example 10 (synthesis) (theory) CloudyUV/Vis. two layers)/Fail 1441 Haze⁴: 58.01  Extinction⁵: >30 (twolayers) (actual) ¹Solids equivalent weight (SEW) calculated frommeasured hydroxyl value (imidazole catalyzed acetylation). ²Resinsreduced to 25% solids in xylene. Viscosity measured at 72° F. using aBrookfield Viscometer LVT (60 rpm, #2 spindle). ³GPC Analysis. ⁴Hazedetermined using Hunterlab DP-9000 (references ASTM E450/ASTM D1925).⁵UV/Visible light extinction (Extinction = −log₁₀ 1/Transmittance)measured between 400-700 nm. Value presented in Table is a ratio of theExperimental resin amplitude/Eastman 515-2 amplitude. ⁶Resins reduced to25% solids in xylene, and exposed to “extreme” temperature ranges (120°F. (1 month) or 39° F. (24 hrs.)). Failure noted if resin separates inmultiple layers/phases. ⁷Resins drawn down on glass, flashed, andannealed at 40° C. Tg measured using TA Instruments 2920 MDSC unit (20°C./min heating rate, ˜6 mg sample weight).

TABLE O Coating K Coating L Coating M Component weight (g) weight (g)Weight (g) Resin of  16.2 — — Example 9 Resin of — 14.6 — Example 10515-2¹ — — 25.0 Xylene  83.8 85.4 75.0 Total 100.0 100.0 100.0 ¹EastmanChemical

TABLE P Adhesion Adhesion Adhesion Adhesion 1 Hour after 1 Day after 1Day 7 Day Exposure² Exposure² Substrate¹ (0-5) (0-5) (0-5) (0-5) KBayflex 4 4 4 4 110-35 Sequel 1 2 4 4 1440 Montell 4 4 4 4 CA186 TSOP-13 2 4 4 Himont 5 4 5 5 SD242 L Bayflex 4 4 4 4 110-35 Sequel 4 4 4 41440 Montell 4 4 4 4 CA186 TSOP-1 4 4 4 4 Himont 5 5 5 4 SD242 M Bayflex 0³  0³  0³  0³ 110-35 Sequel  0³  0³  0³  0³ 1440 Montell  0³  0³  0³ 0³ CA186 TSOP-1  0³  0³  0³  0³ Himont  0³  0³  0³  0³ SD242 N Bayflex4 4 4 4 110-35 Sequel 4 4 4 4 1440 Montell 4 4 4 4 CA186 TSOP-1 4 4 4 4Himont 5 4 5 4 SD242 ¹All panels purchased from ACT Laboratories, Inc.²100° F./100% humidity, 4 days. ³Adhesive failure between adhesionpromoter and primer sealer

As shown in Table N, there are substantial differences between thecopolymers of the present invention and those of U.S. Pat. No.5,955,545, prepared by free-radical polymerization. Because thefree-radical polymerization process results in species that are notgrafted to a chlorinated polyolefin backbone, there are substantialstability problems with the prior art composition. The resin solution ofthe present invention is clear as is a solid film coating prepared fromthe resin solution, even as compared to the CPO precursor. The prior artcomposition is hazy in solution and produces a visibly cloudy solidfilm. This is a clear indicator of the instability of the prior artcomposition and the relative stability of the copolymer of the presentinvention when in solution. Table P indicates the suitability of thecomposition of the present invention, as embodied in Coating K, for usein an adhesion-promoting layer. Although the prior art composition maybe an effective adhesion promoter, its long-term stability and,therefore, its commercial usefulness are questionable in view of thedata presented in Table N.

The present invention has been described with reference to specificdetails of particular embodiments thereof. It is not intended that suchdetails be regarded as limitations upon the scope of the inventionexcept insofar as and to the extent that they are included in theaccompanying claims.

We claim:
 1. A copolymer prepared by polymerizinq one or more radicallypolymerizable alkenes in the presence of a halogenated polyolefininitiator under controlled radical polymerization conditions, in whichthe halogenated polyolefin initiator includes one or more halides boundto tertiary carbon atoms.
 2. The copolymer of claim 1 in which thehalogenated polyolefin initiator comprises about 15% to about 45% byweight halide groups with at least about 80% of the halide groups beingtertiary.
 3. The copolymer of claim 1 in which the halogenatedpolyolefin initiator contains at least one radically transferable atomand the controlled radical polymerization is performed in the presenceof: (a) a transition metal-complex; and (b) one or more N-, O-, P-, orS-containing ligands which coordinates in a σ-bond or π-bond to thetransition metal, or any C-containing compound which can coordinate in aπ-bond to the transition metal.
 4. The copolymer of claim 3 in which thetransition metal is selected from the group consisting of copper, iron,gold, silver, mercury, palladium, platinum, cobalt, manganese,ruthenium, molybdenum, niobium and zinc.
 5. The copolymer of claim 3 inwhich the ligand is selected from the classes consisting ofunsubstituted and substituted pyridines and bipyridines, porphyrins,cryptands, crown ethers, polyamines, glycols and coordinating monomers.6. The copolymer of claim 1 in which the halogenated polyolefininitiator is selected from the group consisting of a halogenatedpolyethylene, halogenated polypropylene and a halogenated polybutylene.7. The copolymer of claim 1 in which the tertiary halide group isselected from the group consisting of chlorine and bromine.
 8. Thecopolymer of claim 1 in which the alkenes are vinyl monomers.
 9. Thecopolymer of claim 8 in which the monomers are (meth)acrylic monomers.10. The copolymer of claim 8 in which the monomers comprise a reactivegroup selected from the group consisting of hydroxyl, glycidyl, amineand carboxyl.
 11. The copolymer of claim 10 in which the monomerscomprise a hydroxyl group.
 12. The copolymer of claim 11 in which thehydroxyl groups of the copolymer are post-reacted with one of a lowmolecular weight alkyl carbamate, isocyanic acid or urea to add pendantcarbamate groups to the copolymer.
 13. A polymer as claimed in claim 1which is prepared using one monomer.
 14. The copolymer of claim 1 whichis prepared using at least two different monomers.
 15. The copolymer ofclaim 1 in which a sequence of different monomers are polymerized toform a copolymer having at least one block copolymer segment.
 16. Thecopolymer of claim 15 in which the block copolymer segment containshomopolymeric blocks of different acrylic monomers.
 17. The copolymer ofclaim 16 in which the acrylic monomers are selected from the class ofepoxy group-containing acrylic monomers, carboxyl group-containingacrylic monomers, and hydroxyl group-containing acrylic monomers. 18.The copolymer of claim 1 wherein the number average molecular weight ofthe copolymer is from 5,000 to 50,000.
 19. A method of coating apolyolefinic substrate comprising the steps of: (a) applying to thepolyolefinic substrate a first film-forming composition comprising acopolymer prepared by polymerizing one or more monomers of a radicallypolymerizable alkene in the presence of a halogenated polyolefininitiator under controlled radical polymerization conditions, in whichthe halogenated polyolefin initiator includes one or more tertiaryhalide groups; and (b) coalescing the composition to form asubstantially continuous film.
 20. The method of claim 19, furthercomprising a step (c) applying a second film-forming composition to anexposed surface of the coalesced, substantially continuous film.
 21. Themethod of claim 19 in which the second film-forming composition is apigmented composition.
 22. The method of claim 20 in which a clearfilm-forming composition is applied to an exposed surface of the filmlayer comprising the second film-forming composition.
 23. The method ofclaim 19 wherein the copolymer is present in the film-formingcomposition in an amount of at least 1.5% by weight.
 24. The method ofclaim 19 wherein the copolymer is present in the film-formingcomposition in an amount less than 20% by weight.
 25. The method ofclaim 19 wherein the copolymer is a primary film forming resin in thefilm-forming composition and is present in the film-forming compositionin an amount of from 50 to 100% by weight.
 26. A coated articlecomprising a polyolefinic substrate having a coating layer comprising apolyolefin copolymer prepared by polymerizing one or more radicallypolymerizable alkenes in the presence of a halogenated polyolefininitiator under controlled radical polymerization conditions, in whichthe halogenated polyolefin initiator includes one or more tertiaryhalide groups.
 27. The coated article of claim 26 in which thehalogenated polyolefin initiator comprises about 15% to about 45% byweight halide groups with at least about 80% of the halide groups beingtertiary.